In a large number of applications, such a connection is made between a rigid tube which is generally made of metal or a plastic and a hose made of rubber or other flexible and elastically deformable material; both the tube and the hose being substantially circular in cross-section. To this end, the hose is force-fitted over the end of the rigid tube, which tube is sometimes constituted by a simple endpiece integrally molded during manufacture of an engine casing, or else is integral with some engine component such as a cooling radiator, for example. After the hose has been force-fitted onto the rigid tube, the connection is sealed and simultaneously the hose is held in place on the tube by means of a clamping collor. The collar thus prevents leaks occurring through the connection circuit and simultaneously prevents relative sliding or disconnection between the hose and the tube, which could be caused equally well by vibration or by the pressure of the fluid conveyed. Patent application GB-A-2 161 568 describes an assembly of the type outlined above, except insofar as it also includes a clamping ring of longitudinal blades between the hose and the clamping collar. A similar construction is proposed in European patent application 0 219 418.
However, this technique of making a sealed connection between a tube and a hose, in addition to generally requiring the collars to be clamped tightly in order to prevent disconnection, thereby running the risk of causing creep in the hose, does not lend itself easily to automating various assembly operations. At present, it does not seem possible to install and clamp a collar on a hose without manual intervention, possibly assisted by motorized means. In addition, disassembling the connection is not very easy since it generally requires the clamping collar to be destroyed.
Further, ideas already exist for making easily disconnectable devices for rapidly connecting together two pieces of pipework, at least one of which is a hose. In such devices, such as described in patent FR-A-1 458 005 and patent GB-A-2 178 503, the end of at least one of the pieces of pipework is mounted in sealed manner on a rigid endpiece. The endpiece is itself provided with means for making a sealed connection with a complementary rigid endpiece disposed at the end of another piece of pipework, or in some cases constituting an integral part therewith, particularly when the other piece of pipework is constituted by a rigid hose. In addition to sealing members being provided on one or both of the endpieces or incorporated therein, these rigid endpieces include complementary fastening means for preventing them coming apart axially under the effect of the pressure that may exist inside the pipework.
Regardless of the particular type of fastening used, it is essential that two sealing zones are provided, firstly between the flexible piece of pipework (i.e. The hose) and the corresponding endpiece, and secondly between the two complementary endpieces.
There are various different ways in which the sealing can be provided in the first of these two zones.
For example, if the material used is suitable, it is possible to glue or overmold the hose inside or outside its endpiece as proposed in patent GB-A-2 178 503. In this case, sealing and axial fastening between the two pieces are obtained simultaneously by the gluing or the overmolding. However, it should be observed that even when such overmolding is possible, it is relatively expensive. In addition, it is often not possible to glue the hose to its endpiece because of the danger of deteoriation at the axial fastening and in the sealing of the fluids conveyed, in particular water.
In general, after fitting a length of the endpiece inside the hose, it is preferred to obtain sealing by means of a clamping collar in a manner similar to that outlined above and in spite of the drawbacks of this technique, as already mentioned.
Various types of disconnectable device for making a sealed connection quickly between a rigid tube and a hose are described in the following French patents: 2 605 705, 2 606 118, 2 608 250, 2 614 084, 2 628 819, 2 628 821, 2 630 522, 2 633 368, and 2 636 713. Although these prior devices do indeed seek to remedy some of the drawbacks mentioned above, they achieve this aim only in part and, above all, they are relatively expensive to manufacture. Further, installation thereof is not very reliable.
Finally, mention is made of Swiss paten CH-A-338 063 which relates to connecting a pipe made of relatively rigid plastic material onto a threaded piece of pipework. Not only are the dispositions described in that patent incompatible with the use of a hose that is flexible, but also, in practice, it should be observed that they require the pipe to be capable of rotating about its own axis.